Prolong, v. t. [imp. & p. p. Prolonged; p. pr. & vb. n. Prolonging.]
Etymology: [F. prolonger, L. prolongare; pro before, forth + longus long. See Long, a., and cf. Prolongate, Purloin. ]
1. To extend in space or length; as, to prolong a line.
2. To lengthen in time; to extend the duration of; to draw out; to continue; as, to prolong one's days. Prolong awhile the traitor's life. Shak. The unhappy queen with talk prolonged the night. Dryden.
3. To put off to a distant time; to postpone. Shak.
Shades of meaning
Fernald has no entry of its own for prolong; he lists it under protract.
He lists it without comment; the entries above explain its neighbors.